Mechanism Of NOx Reduction Research Articles

스월연소기에서 연료스월유동이 NOx 배출에 미치는 영향

본 연구에서는 스월 연소기에서 연료스월유동이 NOx 배출특성에 미치는 영향을 실험적으로 조사하였다. 공기와 연료스월각을 변화시키기 위해 환형베인을 사용하였고 베인각의 변화에 따라 혼합공정을 변화시켰다. 공기스월이 강한 조건에서 연료 Counter-swirl의 경우, 비연소장에서 큰 난류강도의 특성을 나타내고 상대적으로 고주파 영역까지 높은 에너지를 가지고 있으며, 고온 영역이 좁게 나타났다. 이러한 연료 counter-swirl 영향으로 저NOx 배출특성이 나타났으며, NOx 저감 기구가 논의되었다. In this study, experimental investigations were conducted on NOx emission characteristics with fuel swirl flow in swirl combustor. Many types of vanes, which altered air and fuel swirl angles, were employed to verify the mixing processes. For strong air swirl, fuel counter-swirl resulted in relatively large turbulent intensity, high energy to the high frequency region and narrow width of high temperature region compared with co-swirl condition. These effects of fuel counter-swirl resulted in low NOx emission characteristics at strong air swirl condition. And NOx reduction mechanism was also discussed.

The Mechanism of Selective NOx Reduction by Hydrocarbons in Excess Oxygen on Oxide Catalysts: IV. Spectrokinetic Characteristics of Intermediate Complexes on the Commercial STK Catalyst

The Mechanism of Selective NOx Reduction by Hydrocarbons in Excess Oxygen on Oxide Catalysts: IV. Spectrokinetic Characteristics of Intermediate Complexes on the Commercial STK Catalyst

The Mechanism of Selective NOx Reduction by Hydrocarbons in Excess Oxygen on Oxide Catalysts: III. Adsorption Properties of the Commercial STK Catalyst

The Mechanism of Selective NOx Reduction by Hydrocarbons in Excess Oxygen on Oxide Catalysts: III. Adsorption Properties of the Commercial STK Catalyst

Reduction of NOx in a Regenerative Industrial Furnace With the Addition of Methanol in the Fuel

The analysis of the combustion process and NOx emission in a gas-fired regenerative industrial furnace has been carried out numerically. The effect of the additive, methanol CH3OH, to the fuel on the NOx emission is studied. A moment closure method with the assumed β Probability Density Function (PDF) for the mixture fraction is used to model the turbulent non-premixed combustion process in the furnace. The combustion model is based on the assumption of instantaneous full chemical equilibrium. The P-1 model is chosen as the radiation model, and the Weighted-Sum-of-Gray-Gases Model is used to calculate the absorption coefficient. The numerical results showed that the use of CH3OH is effective in the reduction of NOx in a regenerative industrial furnace. The mechanism of NOx reduction by the use of CH3OH is also discussed.

421 銀系触媒上でのエタノールによるNOxの還元機構(環境負荷低減のためのエネルギー変換技術III)(オーガナイズドセッション(c)環境負荷低減のためのエネルギー変換技術)

421 銀系触媒上でのエタノールによるNOxの還元機構(環境負荷低減のためのエネルギー変換技術III)(オーガナイズドセッション(c)環境負荷低減のためのエネルギー変換技術)

On the Mechanism of NO Selective Catalytic Reduction by Hydrocarbons over Cu-ZSM-5 via X-ray Absorption Spectroscopic Study

An understanding of the catalytic mechanism of NOx reduction is critical for the development of next-generation high-fuel efficiency, low-emission vehicles. This paper compiles our investigations in recent years on the mechanism of NO selective catalytic reduction (SCR) by hydrocarbon over Cu-ZSM-5. The studies were focused on the oxidation state and coordination chemistry of the exchanged Cu as the active site during the catalytic reaction using X-ray absorption spectroscopic (XAS) techniques, mainly XANES and EXAFS. Our experiment demonstrated the existence of a redox mechanism which involves cyclic switching of the oxidation states between Cu(II) and Cu(I) in an oxygen-rich gas mixture under elevated temperature. We also observed the coordination structural change of copper ion in ZSM-5 accompanying the change of oxidation state. A correlation between cuprous ion concentration and catalytic activity was found in NO SCR by propene. The impact of another two hydrocarbons, propane and methane, on the copper redox behavior also appears to correlate to catalytic activities in the respective mixtures. Discussions on the nature of the active sites and the mechanism of SCR are presented based on the XAS data analysis. The similarity and difference of the physical properties of copper ion between NO catalytic decomposition and NO SCR are also discussed.

Kinetics and Mechanism of the Reduction of NO by n-Octane over Pt/Al2O3under Lean-Burn Conditions

The effect of temperature, contact time, and reactant concentration on the reduction of NO by n-C8H18over Pt/Al2O3under oxidising conditions was investigated. The oxidation of n-C8H18appears to be delicately balanced between two kinetic regimes. At low [C8H18]/[O2] the coverage of oxygen on the Pt surface is high, while that of carbonaceous species is negligible, resulting in hydrocarbon oxidation being inhibited by oxygen and in the oxidation of NO to NO2. At higher [C8H18]/[O2] the surface is saturated with carbonaceous species, while the coverage of oxygen is negligible, resulting in hydrocarbon oxidation being zero order in hydrocarbon concentration and in no NO2formation being observed. The state of the Pt surface affects the mechanism of NOxreduction. Thus, NOxreduction via dissociation of NO on the Pt surface is favoured by a high coverage of carbonaceous species, while a high coverage of oxygen favours NOxreduction by reaction between n-C8H18-derived species and spilt-over NO2on the Al2O3support and/or metal–support interface. Separate kinetic models capable of fitting the data in these two regions have been developed.

97/01376 NOx reduction mechanism in coal combustion with recycled CO2

97/01376 NOx reduction mechanism in coal combustion with recycled CO2

NO x reduction mechanism in coal combustion with recycled CO 2

Coal combustion with CO 2 O 2 is one of several promising new technologies associated with mitigating the CO 2 rise in the atmosphere. In coal combustion with recycled CO 2, the amount of NO x exhausted from the system is reduced to less than one third of that with combustion in air. This result is associated with decreased conversion of fuel-N to NO x and reduction of recycled NO x in the flame zone. The effects of CO 2 concentration, reduction of recycled NO x, and interaction between fuel-N and recycled NO x on the decrease of the final NO x exhausted from the coal-combustion system with recycled CO 2 have been separated for appropriate NO x-reduction mechanisms.

9437377 Development of NOx storage-reduction 3-way catalyst system (II): NOx reduction mechanism and improvement of conversion efficiency: Toshiaki Tanaka, Shinichi Takeshima, Shinichi Matsumoto, Satoshi Iguchi (Toyota Motor Corporation), Koji Yokota (Toyota Central R&D Labs., INC.), Kouichi Kasahara (CATALER Industrial Co., LTD), pp. 45–48, 12 figs., 6 refs

9437377 Development of NOx storage-reduction 3-way catalyst system (II): NOx reduction mechanism and improvement of conversion efficiency: Toshiaki Tanaka, Shinichi Takeshima, Shinichi Matsumoto, Satoshi Iguchi (Toyota Motor Corporation), Koji Yokota (Toyota Central R&D Labs., INC.), Kouichi Kasahara (CATALER Industrial Co., LTD), pp. 45–48, 12 figs., 6 refs